Other pop mucisians who died at 27 were e.g. Gram Parsons. Also only 27 like Jimi Hendrix, Kurt Corbain, Janis Joplin, Jim Morisson, Amy Winehouse. Alan Wilson (Canned Heat) , Brian Jones.
Wellknown mucisians who did at 28 were Clearance White (Byrds) and Tim Buckley
For Alan Wilson listen to On the Road Again of Canned Heat:
Alan "Blind Owl" Christie Wilson (July 4, 1943 – September 3, 1970) was the leader, singer, and primary composer in the American blues band Canned Heat. He played guitar and harmonica, and wrote most of the songs for the band.